Acta Microscopica 29, 1159 (2020)
With the appearance of new near-field optical microscope, people's field of vision has been broadened to less than one tenth of the wavelength, that is, nanometer scale. In the near-field optical microscope, a probe with an aperture much smaller than the wavelength of light is used instead of an optical lens. When such a sub wavelength probe is placed within a wavelength from the surface of the object, that is, the near-field area, rich sub micron optical information can be detected by detecting the non radiation field bound to the surface of the object. In this paper, the near-field optical properties of hexagonal star and hexagonal petal MoS2 crystals are studied by near-field optical microscopy. The experimental results show that the grain boundaries of single MoS2 crystal can be distinguished in AFM and fluorescence images, but not in near-field optical images and Raman surface scanning. The near-field signal increases with the increase of sample thickness, which can be understood as the higher charge concentration in the thicker region. The grain boundary and edge of multi-layer MoS2 crystal can be distinguished in the near-field optical chart. The superposition growth of multi-layer MoS2 crystal often leads to the complex interaction between the atomic position and electronic structure. As a result, the structural and electronic recombination has taken place at the edge and the grain boundary of the atomic level.